Fuel injection controls for internal combustion engines

ABSTRACT

The invention relates to a control apparatus for an internal combustion engine fuel injection system. The control apparatus operates by varying the stroke of an associated metering device, and has a lever movable by a cam plate in response to the engine inlet manifold pressure. The lever is also movable by a further cam coupled to the engine throttle control, whereby the amount of fuel supplied to the engine is dependent both on manifold depression and throttle position.

United States Patent [151 3,664,317

Skinner et al. 1 May 23, 1972 s41 FUEL INJECTION CONTROLS FOR [56] References Cited INTERNAL COMBUSTION ENGINES UNITED STATES'PATENTS 1 Inventors: J Skinner; George Whitehurst, both of 3,487,821 1/1970 Skinner ..123/14o.3 Solihull. ar i i England 2,624,284 1/1953 Straub ..123/139 x [73] Assignee: Motor Units Limited, London, En- Primary Examiner Laurence M G l g AttorneyHolman & Stem [22] Filed: Mar. 3, 1970 [21] App1.No.: 16,141

[57] ABSTRACT The invention relates to a control apparatus for an internal combustion engine fuel injection system. The control ap- [52] US. Cl ..l23/139 BG, 123/139 AM paratus operates by varying the troke ofan associated meter- [51] ..F02d 1/04 ing device, and has a lever movable by a cam plate in response [58] Field of Search ..123/139, 139.11, 139.11 A, to the engine inlet manifold pressure. The lever is also mova 123/140, 140.2, 140.3, 119, 139.17, 139.18 ble by a further cam coupled to the engine throttle control,

whereby the amount of fuel supplied to the engine is dependent both on manifold depression and throttle position.

9 Claims, 3 Drawing Figures r 2 r" z/v/A/z K Z Jfl/ UN 1 E 1 25 22 1 I0 166 l E 21 1 e 50 i Q 29 i 27 '7 M 1 1 1 24 25 I 28 I v I L L 1 {@a PATENTEDMAY23 I972 3,664,317

sum 2 0F 3 ATT NEYS sum 3 0F 3 PATENTEDMAYZB I972 AT NEYS FUEL INJECTION CONTROLS FOR INTERNAL COMBUSTION ENGINES in over fuelling when the throttle controlling the admission of air to the engine intake manifold is progressively moved towards its closed position.

It is an object of this invention to provide a fuel control in which this disadvantage is reduced.

According to the invention a control for a fuel injection system for an internal combustion engine comprises a metering means for passing measured doses of fuel to the engine from a pump, a cam means, a means actuable, in use, by the engine intake manifold pressure to displace the cam means, a lever movable by the cam means and associated with an abutment forming part of the said metering means, means mounting the said lever for movement about a pivotal axis and arranged to permit movement of the said first pivotal axis in a direction transverse to both the said pivotal axis and to the direction in which the said cam means is movable, and means adapted for connection to the engine throttle for displacing the said pivotal axis in a direction to vary the said doses of fuel as the throttle is opened and closed, independently of variation of the doses by movement of the said cam means.

In the accompanying drawings:

FIG. 1 is a section through an example of a fuel injection control;

FIG. 2 is a view on arrow 2 in FIG. 1 and with portions removed for clarity and FIG. 3 showing required shuttle stop positions for a series of different constant values of manifold pressure.

A fuel injection control comprises a body 10 in which a lever 11, formed as a yoke and having arms 12, 13, is pivotally mounted on a spindle 14. A spindle between the ends of the arms 12, 13 forms a pivot for a second lever 16. Lever 16 is formed as a pair of flanges 16a joined by webs 16b. One end of lever 16 carries a roller 17 which engages an edge cam 18 journalled on a shaft 19 in the body 10.

Spindle 15 carries a roller 20 which engages a cam plate 21. Cam plate 21 is mounted for movement within the body 10 in a direction transverse to the axes of the spindle 15 and roller 17. Cam plate 21 is also coupled to a diaphragm 22 sealingly engaged between the body 10 and a cap 23. The cam plate 21 is biased to the right, as seen in the drawings, by means of springs 24, 25. A screw 27 provides a means for adjusting the bias applied by the spring 25. A passage 26 communicates with the side of the diaphragm remote from the cam plate 21.

The end of lever 16 carries an adjusting screw 28 upon which rests a cup-shaped member 29 supporting a rod 30. Rod 30 is engaged with a piston-like member 31 which co-acts with a control stop of a shuttle-type fuel metering pump 43. The lever 16 is biased anticlockwise towards the member 31 by means of a spring 32.

A spindle 33, journalled in the body 10 carries at one end an actuating lever 34 and at the other a cam 35 engageable with an upper face of lever 12 intermediate the spindles 14, 15.

In use, passage 26 communicates with the air inlet manifold 43 of an associated engine and shaft 19 is coupled to a throttle control 44 for the engine, the arrangement being such that rotation of shaft 19 in a direction corresponding to opening of the throttle rotates lever 16 clockwise about a pivot formed by the spindle 15. The resultant downward movement of member 29, rod 30 and member 31 causes the control stop of the metering pump to move to increase fuel supply to the engine, which, for a given external load results in an increase in engine speed. The consequent ressure dro in the engine inlet manifold acts to urge the raphragmZ against the springs 24,

25, moving the cam plate 21 to the left and allowing spring 32 to rotate lever 16 anticlockwise about the pivot formed by roller 17 to reduce fuel supply to the engine.

For each value of manifold depression the amount of fuel supplied to the engine is dependent on the throttle position. FIG. 3 shows the required position 40 of the shuttle stop of the metering pump, plotted against throttle opening 41 for a number of values of constant manifold depression. It will be noted that characteristics of a control in which fuel supply is dependent only on manifold depression would be a series of vertical straight lines passing through the upper extremes of the curves shown in FIG. 3. In such a case the engine would be substantially over fueled as the throttle approached its closed position.

It will also be noted that all of the curves shown in FIG. 3 are similar. A profile of the cam 18 which causes any one of the curves to be followed exactly will cause the remainder of the curves to be followed approximately. The invention thus results in a reduction of overfuelling for small throttle opening conditions, resulting in improved fuel consumption figures. The emission of unburnt exhaust gases during small throttle opening conditions will also be reduced.

Controlled overfuelling, as for example during starting, is provided by means of cam 35 which is rotated by lever 34 to urge lever 11 anticlockwise and thus to move lever 16 clockwise about roller 17 to increase fuel flow.

Having thus described my invention what we claim as new and desire to secure by Letters Patent is:

l. A control device for a fuel injection system for an internal combustion engine having an air intake manifold and a throttle, said control device comprising metering means for passing measured doses of fuel to the engine from the pump, a body, cam means movably mounted in the body, means actuable in use by the engine air intake manifold pressure to displace said cam means relative to the body, a lever movably by said cam means and associated with an abutment forming part of said metering means, carrier means mounting said lever for movement relative to the body about a pivotal axis, said carrier means being movably mounted on the body so as to permit movement of said pivotal axis in a direction transverse both to said pivotal axis and to the direction in which said cam means is movable relative to the body, and means adapted for connection to the engine throttle for displacing said pivotal axis to vary said dose of fuel as the throttle is opened and closed, independently of variation of the dose by movement of said cam means.

2. A control as claimed in claim 1 in which the means actuable by the manifold pressure comprises a diaphragm displaceable against a biasing means by the manifold pressure.

3. A control as claimed in claim 1 in which the means mounting the lever about the first mentioned pivotal axis in cludes a second pivotal axis about which the first-mentioned pivotal axis is movable.

4. A control as claimed in claim 3 in which the second pivotal axis is defined by co-operation of the lever with the cam means.

5. A control as claimed in claim 3 in which the means for displacing the first mentioned pivotal axis comprises a further cam means coupled to the engine throttle.

6. A control as claimed in claim 3 which includes a second lever mounted on a third pivotal axis and pivotally engaged with the first lever.

7. A control as claimed in claim 6 in which the second lever engages the first lever at the second pivotal axis.

8. A control as claimed in claim 6 which includes means engageable with the second lever and operable to displace the first lever in a direction to increase the dosage of fuel to the engine.

9. A control as claimed in claim 8 in which the said means engageable with the first lever is a third cam means. 

1. A control device for a fuel injection system for an internal combustion engine having an air intake manifold and a throttle, said control device comprising metering means for passing measured doses of fuel to the engine from the pump, a body, cam means movably mounted in the body, means actuable in use by the engine air intake manifold pressure to displace said cam means relative to the body, a lever movably by said cam means and associated with an abutment forming part of said metering means, carrier means mounting said lever for movement relative to the body about a pivotal axis, said carrier means being movably mounted on the body so as to permit movement of said pivotal axis in a direction transverse both to said pivotal axis and to the direction in which said cam means is movable relative to the body, and means adapted for connection to the engine throttle for displacing said pivotal axis to vary said dose of fuel as the throttle is opened and closed, independently of variation of the dose by movement of said cam means.
 2. A control as claimed in claim 1 in which the means actuable by the manifold pressure comprises a diaphragm displaceable against a biasing means by the manifold pressure.
 3. A control as claimed in claim 1 in which the means mounting the lever about the first mentioned pivotal axis includes a second pivotal axis about which the first-mentioned pivotal axis is movable.
 4. A control as claimed in claim 3 in which the second pivotal axis is defined by co-operation of the lever with the cam means.
 5. A control as claimed in claim 3 in which the means for displacing the first mentioned pivotal axis comprises a further cam means coupled to the engine throttle.
 6. A control as claimed in claim 3 which includes a second lever mounted on a third pivotal axis and pivotally engaged with the first lever.
 7. A control as claimed in claim 6 in which the second lever engages the first lever at the second pivotal axis.
 8. A control as claimed in claim 6 which includes means engageable with the second lever and operable to displace the first lever in a direction to increase the dosage of fuel to the engine.
 9. A control as claimed in claim 8 in which the said means engageable with the first lever is a third cam means. 